"The Walking Dead" is back! Remember? The AMC drama that was the channel's biggest runaway hit before "Breaking Bad" distracted everyone for eight weeks? Now that Walter White is worm bait, the zombies are back to reclaim their crown. However, as we roll into the show's fourth season, zombie killing is starting to feel dangerously routine.

After grabbing huge ratings and attention for its third season, which introduced the show's preeminent human bad guy, the Governor (David Morrissey), the series has returned with a season premiere that presents quite an audacious notion. It actually seems to be saying that even in a world ravaged by flesh-eating zombies, life can fall into a pretty humdrum routine.

As we catch up with the survivors, they've pretty much settled into life at the prison. Rick is working on his gardening skills, Hershel is also working on his gardening skills, Michonne is searching for the Governor, Darryl and Carol and are speaking baby talk (she calls Darryl "pookie"), Carl is busy growing up, and Tyreese is killing zombies on the fence line just to pick up on a lady. All in all, life in a post-apocalyptic zombie wasteland is pretty routine.

Yes, there are a few new faces. But of all the new characters introduced, only Bob Stookey, played by Larry Gilliard Jr. of "The Wire" fame, is worth remembering. He's a former army medic. He seems fairly upbeat and pleasant, all things considered, and could actually be a valuable addition to a cast of characters that's become so beaten down that at this point, the zombies groans seem to have more life to them.

Other new characters -- such as young Zach and brown-nosing, gawky Patrick -- are goners before the hour is out. But we're likely to see more of Patrick next week, as he is the first to succumb to what appears to be the big new threat of this season: disease. Yes, yes, the zombie threat is a disease. But we're talking the more common kind of disease that kills wildlife and eventually people. Is the black death coming to "The Walking Dead?" It appears that way.

Although that threat is microscopic, in other ways, the show is bigger than ever. One highlight of the episode was a showstopping action set piece featuring zombies, and eventually a helicopter, crashing through the roof of a store. The sequence was thrilling but only served to underscore the lengths the show has to go to now in order to make the zombie attacks seem like anything more than a duty.

Probably the moment that will stay longest in viewers' minds is the hungry, scared and hopelessly insane look in the eyes of Clara, the mud-smeared survivor Rick stumbled across in the woods. Played by Irish actress Kerry Condon, Clara's appearance is virtually indistinguishable from that of the zombies: unkempt hair, dirt-streaked face, lacking in parts of her basic humanity. Rick's interlude with her in the woods, which ended with her attempting to kill him, is a truly frightening flip side to the workaday life that has developed inside the prison.

Whereas last season looked externally to the threat -- the Governor, who's still lurking out there somewhere -- this season looks like it's turning inward for the threat. Really inward. Like, your digestive tract. And your mind. Will vomiting, cold sweats and quiet insanity carry the same appeal as the Governor's whacked-out life? It's really doubtful, but the season is young and there's always next week.